1. Field of the Invention
The present invention relates to a wafer processing method.
2. Description of the Related Art
In a semiconductor device fabrication process, a plurality of devices such as ICs, LSIs, and MEMS (Micro Electro Mechanical Systems) devices are formed on the front side of a substantially disk-shaped semiconductor wafer. These plural devices are formed in a plurality of separate regions defined by a plurality of crossing division lines called streets. The semiconductor wafer thus having the plural devices is cut along the streets to thereby divide the plural separate regions where the plural devices are formed from each other. Thus, a plurality of device chips corresponding to the plural devices are manufactured.
Until recent years, cutting of the semiconductor wafer has been performed by using a cutting apparatus having a cutting blade. However, since a division groove having a width of about 20 to 40 μm is formed along each division line by the cutting blade, each division line must have a sufficient width to cause a problem such that the number of devices that can be obtained is limited. Furthermore, since the semiconductor wafer is cut by the cutting blade as supplying a cutting water to remove dust, there is a possibility that the MEMS devices may be damaged by the scattering of the cutting water. Further, cutting of a low-k film without separation is difficult in the case of using the cutting apparatus. For these reasons, a laser processing apparatus using a laser beam has been increasingly applied to the processing of the semiconductor wafer.